Removal of alkali metal impurities from liquid diene polymers



REMOVAL OF ALKALI METAL FR M LIQUID DIENE POL E Paul F. Warner, Phillips, Ten, assignor to Phillips Petro-- leum Company,ucorporation of Delaware o Drawing. Application October- 30, 1958 I Serial No.'l 'l0,581

Claims. ((31.260-5290) This invention relates to the removal of alkali metal 2,937,178 Patented May 17, 1960 duces a substantially catalyst-free product but, in some cases, leads to the formation of emulsions which reduce the ultimate yield of product. Furthermore; the presence of even trace amounts of water is deleterious to filtration rates and to the ash content of the finished polymer.

Broadly, the present invention is directed to treatment of the polymers commonly, the process being practiced on the reaction zone efllue'nt, by a method which does not involve the use of water.

The method of the present invention comprises treating the liquid polymer with an alcohol and with a halide reactive alkali metal organic compounds present to prevent further catalytic elfect of 'the alkali metal on the,

tics, will impart too fast a curing rate of a compound of said rubber if it contains alkali metal hydroxides. A liquid polymer which is to be used as a drying oil should not containiany substantial amount of'alkali metal or alkali metal compounds, as these tend to render the liquid; cloudy and cause undesirable reactions when compound ing these oils in paints, various types of varnishes and protective surface coatings and adhesive formulations.

By the term alkali metal impurities, employed herein, it is meant to include free alkali metal and/ororgano alkali metal compounds formed during thepolymerization and present in the polymer product, and also organo of calcium, zinc, or iron, this combination treatment resulting in the formation of a precipitate which can be removed from the liquid polymer.

The following are objects of this invention.

.An objectof this invention is to provide alkali metal free liquid polymers of conjugated diolefins. A further object of this invention isto provide a process for removing alkali metal impurities from liquid polymers of conjugated dienes. A further object of this invention is'to provide a process for the removal of alkali metal impurities from homopolymers of l,3-butadiene and copolymers of 1,3-butadiene and 2-methyl-5-vinylpyridine.

Other objects and advantages of this invention will be apparent to one skilled in the art-upon reading this disclosure. i As stated, the present invention relates to liquid poly- .mers of conjugated dienes prepared according to the method disclosed in Patent No. 2,631,175. a As "shown in Representative conjugated dienes include 'l,3-but-adiene,

isoprene, piperylene, '2-methyl-l,3-pentadiene,' 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-hexadiene, and l,3-oc

tadiene. Various vinyldiene containing comonomers can be used in combination with the conjugated diene, these ineluding, for example, styrene, vinyl chloride, acrylonitrile,

alkali metal compounds employed as catalysts, such as sodium butyl, sodium triphenyl methyl, and the like,

and alkalimetal hydrides. These latter compounds are. exemplary of catalysts within the group consisting of the covering a substantially catalystfree product, either as a solution of the polymer in an organic-solvent oras the liquid polymer .free of solvent. 'It has long been known thatcontactingthe. polymerization zone aten with an} alcohol results in deactivation of the catalyst. Alcohols lcnown in the art for such-treatment include, preferably, those containing up to four carbon atoms per molecule such as methyl alcohol, ethyl alcohol, the propyl alcohols, the butyl alcohols, propylene gycol-and butylene glycol. According to prior art processes, ithas been common totreat the polymer, following treatment withv the alcohol, in a water washing-s ep; Such water washing promethyl vinyl ,ether, and the like. *A group of copolymers; of current interest are those prepared by polymerizing a major amount of a conjugated diene as above defined and a copolymerizable heterocyclic nitrogen base.

copolymerizable with a conjugated diene and contain one substituent wherein R is either hydrogen or a methylgroup, i.e., the substituent" iszeither a vinyl or an alphamethyl-vinyl (isopropenyl) group." The vinyl-substituted heterocyclic nitrogen bases of-the pyridine and quinoline series which are preferred'are those having only one substituent and of these compounds, those belonging to the, pyridine series are most frequentlyused- Variousderivativesgcan also beusedbut it is generally preferred that vinyl, should not be greater-than 12 and most frequently.

thesealkyl substituents are methyl and/or ethyl. v

These heterocyclic nitrogen bases have the formula where R is selected from the group consisting of hydrogen, alkyl, vinyl, alpha-methylvinyl, alkoxy, halo, hydroxy, cyano, aryloxy, aryl, and combinations of these groups such as haloalkyl, alkaryl, hydroxyaryl, and the like; one and only one of these groups being selected:

from the group consisting of vinyl and alpha-methylvinyl; and the total number of carbon atoms in the nuclear substituted groups, in addition to the vinyl or alphathe alkali metal present. Frequently as much as a 100 percent excess is used.

The next step involves treatment with a halide of calcium zinc, or iron, the addition of such a salt producing a precipitate which can be removed by filtration. Examples of these halides include calcium fluoride, calcium chloride, calcium iodide, calcium bromide, zinc chloride,

; zinc iodide, zinc bromide, ferrous chloride, ferric chlomethylvinyl group, being not greater than 12. Examples of such compounds are Z-vinylpyridine;

2-vinyl-5-ethylpyridine; 2-methyl-5-vinylpyridine;

4-vinylpyridine; 2,3,4-trimethyl-S-vinylpyridine; 3,4,5,6-tetramethyl-2-vinylpyridine; 3-ethyl-5-vinylpyridine; 2,6-diethyl-4-vinylpyridine; 2-isopropyl-4-nonyl-5-vinylpyridine; 2-methyl-5-undecyl-3-vinylpyridine; 2,4-dimethyl-5,6-dipentyl-3-vinylpyridine; 2-decyl-5-(alpha-methylvinyl)pyridine; 2-vinyl-3-methyl-S-ethylpyridine; 2-methoxy-4-chloro-6-vinylpyridine; 3-vinyl-5-ethoxypyridine; 2- vinyl-4,S-dichloropyridine; 2- alpha-methylvinyl) -4-hydroxy-fi-cyanopyridine; 2-vinyl-4-phenoxy-S-methylpyridine;

2-cyano-5- alpha-methylvinyl) pyridine; 3-vinyl-5-phenylpyridine; Z-(para-methylphenyl)-3-vinyl-4-methylpyridine; 3-vinyl-5-(hydroxyphenyDpyridine; Z-vinylquinoline;

2-vinyl-4-ethylquinoline; 3-vinyl-6,7-di-n-propylquinoline; 2-methyl-4-nonyl-6-vinylquinoline;

4- alpha-methylvinyl) -8-dodecylquinoline; 3-vinylisoquinoline; 1,6-dimethyl-3-vinylisoquinoline; 2-vinyl-4 benzylquinoline; V 3-vinyl S-chloroethylquinoline; 3-vinyl-5,G-dichloroisoquinoliue; 2-vinyl-6 ethoxy-7-methy1quinoline; 3-vinyl-6-hydroxyrnethylisoquinoline;

and the like.

When copolymers are prepared, the diene component'is generally present in a major portion by weight based on the monomers charged. a U

As previously stated, the alcohol treatment of the prior art is used in the present invention for the deactivation of the catalyst. This treatment results in the pro-- ride, ferrous iodide, ferrous bromide, and ferric bromide. The more alcohol soluble. salts give better re,- sults. Zinc. chloride is preferred although excellent results are obtained with calcium chloride and both chlorides of iron; Zinc and. iron chlorides are somewhat easier to use because the'end point can be easily determined with pH paper, the easiestibeing the end point when using zinc chloride.

The precipitate formed when operating according to this invention, using ,zinc chloride as the salt and methyl alcohol as the alcohol, is a mixture of zinc methylate an sodium chloride.

Example A 'li'quid copolymer of 1,3-butadiene and Z-methyl-S- vinylpyridine was prepared using a monomer ratio of parts by weight butadiene and 15 parts by weight of 2-methyl-S-vinylpyridine. This material was polymerized at a temperature of 185 F. and a pressureof 30 p.s.i.g. using finely divided sodium as the catalyst in an amount of approximately 1 weight percent based upon the monomers charged, Commercial grade normal heptane was used as the solvent in an amount to give an approximate 40 weight percent solution of the'liquid polymer. Following. polymerization, methyl alcohol was added in an amount to give a percent excess based upon the sodium present.

Portions of the reaction zone effiuent following treatment with methyl alcohol were treated with various metal salts in order to form the corresponding alcoholate. The various salts, the amounts used, filtration rates, and ash content of the product following removal ofthe solvent are shown in the following table. The filter used was a. pressure filter having a filter area of three square. inches and a pressure drop across the filter of 10 p.s.i.g. was maintained:

1 32 grams of saturated solutlonof FeCh-ln methyl alcohol.

As many possible embodiments can be made of this invention without departingfrom the scope thereof, it is to be understood that all matterherein set forth is to be:

interpreted as illustrative and not as unduly limiting the invention.

I claim:

l. A method by polymerization of a conjugated diene in thepresence of an alkali metal catalyst and which contains alkali metal as an impurity; which comprises treating said liqfor treating a liquid polymer produced;

uid polymer with an alcohol and thereafter a halide of a metal selected from the group consisting of calcium, zinc, iron, and separating the resulting precipitate from said liquid polymer.

2. The method of claim 1 wherein said liquid polymer is a homopolymer of 1,3-butadiene.

3. The method of claim 1 wherein said liquid polymer is a copolymer of 1,3-butadiene and styrene.

4. The method of claim 1 wherein said liquid polymer is a copolymer of 1,3-butadiene and 2-methyl-5-vinylpyridine.

5. A method for treating a liquid polymer produced by polymerization of a conjugated diene in the presence of an alkali metal catalyst and which contains alkali metal as an impurity, which comprises treating said liquid polymer with methyl alcohol and thereafter zinc chloride, and separating the resulting precipitate from said liquid polymer.

6. A method for treating a liquid polymer produced by the solution polymerization of 1,3-butadiene and 2- methyl-S-vinylpyridine in the presence of a sodium polymerizatlon catalyst and which contains sodium as an impurity, which comprises treating the polymerization zone efliuent with methyl alcohol in an amount at least equal to that required to react with all sodium present, thereafter adding a halide of a metal selected from the group consisting of calcium, zinc, and iron, and separating the resulting precipitate from said liquid polymer.

'7. The method of claim 6 wherein said metal halide is calcium chloride.

8. The method of claim 6 wherein said metal halide is zinc chloride.

9. The method of claim 6 said metal halide is ferrous chloride.

10. The method of claim is wherein said metal halide is ferric chloride.

References Cited in the file of this patent UNITED STATES PATENTS Mertz Nov. 12, 1957 2,827,447 Nowlin Mar. 8, 1958 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N0o 2,,937 178 May l7 1960 Paul F, Warner It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters vPatent should read as corrected below.

Column 5 line 3 after ;zinc,,-" insert; and column 6, line 12 after "claim 6" insert wherein line 14 for is Feed 6 I Signed and sealed this 29th day of November 1960:.

(SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Attesting Oflicer Commissioner of Patents 

1. A METHOD FOR TREATING A LIQUID POLYMER PRODUCED BY POLYMERIZATION OF A CONJUGATED DIENE IN THE PRESENCE OF AN ALKALI METAL CATALYST AND WHICH CONTAINS ALKALI METAL AS AN IMPURITY, WHICH COMPRISES TREATING SAID LIQUID POLYMER WITH AN ALCOHOL AND THEREAFTER A HALIDE OF A METAL SELECTED FROM THE GROUP CONSISTING OF CALCIUM, ZINC, IRON, AND SEPARATING THE RESULTING PRECIPITATE FROM SAID LIQUID POLYMER.
 4. THE METHOD OF CLAIM 1 WHEREIN SAID LIQUID POLYMER IS A COPOLYMER OF 1,3-BUTADIENE AND 2-METHYL-5-VINYLPYRIDINE. 